The present invention is generally directed to a spring clip for a heat sink module to an electronic component or assembly of electronic components. The invention is more specifically directed to a spring clip and heat sink assembly for clamping the heat sink assembly to an electronic module or assembly of electronic components such as a microprocessor chip and PGA socket, to which the chip is connected.
A microprocessor chip has a flat upper surface and a lower surface which is provided with a plurality of downwardly extending connecting pins. A PGA socket has pins on its lower surface for plugging into a circuit board and apertures on its upper surface for receiving the pins of a microprocessor chip. Each side of two opposite side surfaces of the PGA socket is provided with first latching means. For one type of PGA socket the first latching means is a pair of recesses. Each recess is defined in part by a downwardly facing edge surface which intersects the adjacent side surface of the PGA socket. Another type of PGA socket has a pair of protrusions on each on the opposite side surface of the socket which constitute first latching means.
A typical heat sink component includes a base which has a flat bottom interface surface and an upper surface from which a plurality of cooling elements such as vanes or pins extend upwardly.
The heat sink is applied to the microprocessor chip after the microprocessor has been plugged into the PGA socket. The bottom interface surface of the heat sink component rests on the upper surface of the chip to provide optimum heat conduction between the chip and the heat sink assembly. The heat sink component and the microprocessor chip are clamped to the PGA socket by spring clips. A typical spring clip includes a pair of spaced vertical leg portions which are connected by a horizontal grid portion. The grid portion is made up of spaced ribs with defined apertures there between. The ribs are configured to mate with the upper surface of the heat sink component so that the ribs rest on the upper surface of the heat sink component and the cooling elements extend upwardly between the ribs. Each leg portion of the clip is provided with a second latching means which is complementary to the first latching means of the PGA socket. For one type of spring clip, each leg portion of the clip has a pair of inwardly extending projections which are designed to engage the downwardly facing edge surfaces of the PGA socket in which the second latching means is a pair of recesses. When the clip is applied to the heat sink module, the projections of the clip are normally above the downwardly facing edge surfaces of the PGA socket. However, the grid portion of clip is bowed downwardly in the middle so that the ends of the grid portion which are connected to the leg portions of the clip are above the upper surface of the heat sink component but never extend above the cooling elements. The application of downward pressure to the ends of the grid portion causes the legs to move downwardly and inwardly relative to the mid portion of the grid so that the projections engage the downwardly facing surface of the PGA socket. Due to the "spring" or resilient nature of the spring clip, the projections are biased upwardly against the downwardly facing edge surfaces and effectively clamp the heat sink component and the microprocessor chip to the PGA socket. For another type of spring clip, the second latching means is a pair of apertures for receiving the projections of PGA sockets for which the projections constitute first latching means.
Although the use of spring clips for anchoring heat sink components to electronic components have been used quite extensively, there are many problems and objections associated with their use. The clips are generally difficult to apply. Special tools are required to apply the clips to the heat sink and electrical component assembly and application of the clips is a tedious and time consuming task. Special tools are also required to disengage the clip from the electrical component assembly when it becomes necessary to do so, i.e. replacement of a chip. In addition, the clips have a tendency to become disengaged from the PGA socket due to vibrations during normal use of the electronic devices to which the electronic components are applied.
For many of the prior art spring clips, some of the cooling elements of the heat sink component must be removed to provide installation and functional clearance to enable the clip to be applied to the heat sink module. This reduces the cooling efficiency of the heat sink component.
Since clips and PGA sockets vary widely in size, clips must also vary in size. The need for clips of different sizes increases the complexity of the process of selecting and supplying clips to the heat sink and electronic components. These and other difficulties experienced with the prior art spring clips have been obviated by the present invention.
It is, therefore, a principal object of the present invention to provide a spring clip for clamping a heat sink component to an electronic component wherein one size of spring clip can be used for heat sink components which vary in width.
Another object of this invention is the provision of a spring clip which can be applied easily to a heat sink component.
A further object of the present invention is the provision of a spring clip for clamping a heat sink component to an electronic component which is resistant to disengagement from its clamping function during normal use of the electronic component.
It is another object of the present invention to provide a spring clip which can be easily pre-assembled to a heat sink component to form a heat sink assembly for application as a unit to an electronic component or electronic assembly. The assembly acts as a unit, and does not require special tools or hand assembly techniques to apply to the electronic component or assembly.
A still further object of the invention is the provision of a spring clip for clamping a heat sink component to an electronic module which is simple in construction, inexpensive to manufacture and easy to use.
A further object of the invention is the provision of a spring clip for clamping a heat sink component to an electronic module which requires no special machining of the heat sink, and no loss of cooling fins to provide installation and functional clearances.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.